OpenWrt – Rev 1

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/*
 * (C) Copyright 2010
 * Michael Kurz <michi.kurz@googlemail.com>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>
#include <malloc.h>
#include <spi.h>

#include <asm/addrspace.h>
#include <asm/types.h>
#include <asm/ar71xx.h>

/*-----------------------------------------------------------------------
 * Definitions
 */

#ifdef DEBUG_SPI
#define PRINTD(fmt,args...)     printf (fmt ,##args)
#else
#define PRINTD(fmt,args...)
#endif

struct ar71xx_spi_slave {
        struct spi_slave slave;
        unsigned int mode;
};

static inline struct ar71xx_spi_slave *to_ar71xx_spi(struct spi_slave *slave)
{
        return container_of(slave, struct ar71xx_spi_slave, slave);
}

/*=====================================================================*/
/*                         Public Functions                            */
/*=====================================================================*/

/*-----------------------------------------------------------------------
 * Initialization
 */
 
void spi_init()
{
        PRINTD("ar71xx_spi: spi_init");

        // Init SPI Hardware, disable remap, set clock
        __raw_writel(0x43, KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_CTRL));
        
        PRINTD(" ---> out\n");
}

struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
                unsigned int max_hz, unsigned int mode)
{
        struct ar71xx_spi_slave *ss;

        PRINTD("ar71xx_spi: spi_setup_slave");
        
        if ((bus != 0) || (cs > 2))
                return NULL;

        ss = malloc(sizeof(struct ar71xx_spi_slave));
        if (!ss)
                return NULL;

        ss->slave.bus = bus;
        ss->slave.cs = cs;
        ss->mode = mode;

        /* TODO: Use max_hz to limit the SCK rate */

        PRINTD(" ---> out\n");
        
        return &ss->slave;
}

void spi_free_slave(struct spi_slave *slave)
{
        struct ar71xx_spi_slave *ss = to_ar71xx_spi(slave);

        free(ss);
}

int spi_claim_bus(struct spi_slave *slave)
{

        return 0;
}

void spi_release_bus(struct spi_slave *slave)
{

}

int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
                void *din, unsigned long flags)
{
        struct ar71xx_spi_slave *ss = to_ar71xx_spi(slave);
        uint8_t *rx = din;
        const uint8_t *tx = dout;
        uint8_t curbyte, curbitlen, restbits;
        uint32_t bytes = bitlen / 8;
        uint32_t out;
        uint32_t in;
        
        PRINTD("ar71xx_spi: spi_xfer: slave:%p bitlen:%08x dout:%p din:%p flags:%08x\n", slave, bitlen, dout, din, flags);
        
        if (flags & SPI_XFER_BEGIN) {
                __raw_writel(SPI_FS_GPIO, KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_FS));
                __raw_writel(SPI_IOC_CS_ALL, KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_IOC));
        }
        
        restbits = (bitlen % 8);
        if (restbits != 0)
                bytes++;

        // enable chip select
        out = SPI_IOC_CS_ALL & ~(SPI_IOC_CS(slave->cs));

        while (bytes--) {
                
                curbyte = 0;
                if (tx) {
                        curbyte = *tx++;
                }
                
                if (restbits != 0) {
                        curbitlen = restbits;
                        curbyte <<= 8 - restbits;
                } else {
                        curbitlen = 8;
                }
                
                PRINTD("ar71xx_spi: sending: data:%02x length:%d\n", curbyte, curbitlen);
                
                /* clock starts at inactive polarity */
                for (curbyte <<= (8 - curbitlen); curbitlen; curbitlen--) {

                        if (curbyte & (1 << 7))
                                out |= SPI_IOC_DO;
                        else
                                out &= ~(SPI_IOC_DO);

                        /* setup MSB (to slave) on trailing edge */
                        __raw_writel(out, KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_IOC));

                        __raw_writel(out | SPI_IOC_CLK, KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_IOC));

                        curbyte <<= 1;
                }
                
                in = __raw_readl(KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_RDS));
                PRINTD("ar71xx_spi: received:%02x\n", in);
                
                if (rx) {
                        if (restbits == 0) {
                                *rx++ = in;
                        } else {
                                *rx++ = (in << (8 - restbits));
                        }
                }
        }
        
        if (flags & SPI_XFER_END) {
                __raw_writel(SPI_IOC_CS(slave->cs), KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_IOC));
                __raw_writel(SPI_IOC_CS_ALL, KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_IOC));
                __raw_writel(0, KSEG1ADDR(AR71XX_SPI_BASE + SPI_REG_FS));
        }

        PRINTD(" ---> out\n");
        
        return 0;
}